The present invention relates to a lead-in reading system for a disk player in which, in reading an accumulated total time code (TOC) recorded in the lead-in region of the disk in the playback of the disk, the top portion of the TOC is detected.
In an optical disk such as a compact disk, the above-described TOC is recorded in the lead-in region of the disk which is firstly read with the pickup. The TOC includes data representing the total number of pieces of music recorded in the disk, the reproduction time (hours and minutes) of all the pieces of music, and the address and reproduction time of each of the pieces of music.
In general, these data should be read in the order of the total number of pieces of music, the reproduction time of all the pieces of music, and the address of each of the pieces of music.
For this purpose, heretofore in the case where the TOC in the lead-in region of the disk is read with the pickup, the data read are abandoned until the total number of pieces of music is read. That is, the time which has elapsed until the total number of pieces of music is read is wasted, and accordingly, it takes a relatively long period of time to read all the aforementioned data. Hence, the playback of the disk cannot be started quickly.
Further, the invention relates to a random music selection system for a disk player in which, when an operator specifies random music selection, the same piece of music is not mixed in a predetermined number of pieces of music to be reproduced.
In conventional playback method for an optical disk such as a compact disk, when the operator specifies random music reproduction, random numbers are generated in a processor and pieces of music are selected at random and played in the order thus selected. However, the conventional method is disadvantageous in that the same piece of music may be reproduced successively or reproduced again after several pieces of music successively or reproduced again after several pieces of music.
Still further, the invention relates to a music selection method for a disk player in which, in the playback of a disk, when the operator selects a piece of music, a search is made for the selected piece of music according to the total reproduction time and total number of pieces of music as read from the accumulated total time code recorded in the lead-in area of the disk.
Heretofore, when, in the playback of an optical disk such as a compact disk, the operator selects a piece of music, a search is made for the piece of music according to its address (or music number) read from an accumulated total time code recorded in the lead-in region of the disk.
The TOC includes the total number of pieces of music recorded on the disk, the total reproduction time (hours and minutes) of the pieces of music, and the address and reproduction time of each of the pieces of music. That is, the TOC includes a considerably large number of data. Therefore, a memory considerably large in capacity is necessary to store all of the data, with the result that the disk player is unavoidably high in manufacturing cost. Since all TOC data are read in the conventional method, it takes a relatively long period of time for reading the data, as a result of which reproduction cannot be started quickly.
Further, the invention relates to a miss-tracking control method for a disk player in which, when a tracking miss, or so-called "stylus jump", is caused, for instance, by external vibration, an allowable address range is changed according to the frequency of the tracking miss.
In a disk player for optical disks such as compact disks, when sub-codes recorded on a disk are continuously being read so that, while a present address is being stored, an address to be reproduced (expected address) is read successively, it is determined whether reproduction is normal. If a tracking miss is caused, for instance, by external vibration, then the difference between the present address and the expected address is increased. Therefore, in such a case, control is so made that the pickup of the disk player is returned to the expected address. For instance, the disk player may be so designed that, when the difference between the expected address and the present address is one second or more, it is determined that a tracking miss has occurred, and the returning operation is carried out.
However, this method is not advantageous for a disk player mounted on a vehicle. That is, when the vibration level of the vehicle is high, tracking miss will occur frequently. Therefore, if a returning operation is carried out whenever the difference between the expected address and the present address is about one second, then little reproduction can be carried out. Furthermore, for the returning operation, the audio signal is muted, and therefore the silent period is increased.